TUCSON- Off-road vehicles will be banned on part of a southwestern Arizona national monument early in 2008 because of extensive environmental damage caused by reckless riders, federal officials say.

Bureauof Land Management staffers are working on a closure, likely in January, for the northern third of the Sonoran Desert National Monument, said program field manager Kevin Harper.

Harper andothers said riders who have ignored postings and other restrictions, taking their three- or four-wheelers and dirt bikes off designated roads, have carved new trails and mangled often-fragile vegetation. In doing so, they've created ugly, landscape-scarring ruts and other problems for the desert ecology. ? Damage from off-roading isa phenomenon being seen increasingly on public lands across the West as more people take up such recreational use, land use managers, conservationists and others say.

"The monument is really acanary in a coal mine, an indication of everything going on with off-road vehicles," said Jim Baca, New Mexico's natural resource trustee and a former national director of the Bureau of Land Management in President Clinton's first term. "They're causing incredible damage."

Indescribing the harm such vehicles can cause, Baca said, "Think of a new back yard. It's very destructive to the topsoil, it's very conducive to destruction... There are enough irresponsible riders that I do believe it should be banned."

A recently conducted survey of nearly 300 BLM and Forest Service rangers polled in Arizona, southern California, New Mexico, Nevada and Utah bears that sentiment out.

Among theresults of the 23 percent who answered the mailed survey - 91 percent of those responding said off-road vehicles present a significant law enforcement problem, 53 percent said off-road vehicle problems in their jurisdictions are out of control, and 65 percent believe penalties for violators aren't sufficient.

The intent of a two- to three-yearclosure is to restore ripped-up soils, improve the habitat, educate the general community and users in particular, and "have people be more responsible as far as using public lands," Harper said.

"We'reactually seeing a pretty good reaction from environmental groups and user groups," he said. "They understand it's an important resource in the BLM and it has to be managed differently."

Don Hood,president of the Arizona Off-Highway Vehicle Coalition, said that as with any form of recreational activity, a minority of off-road enthusiasts don't obey rules.

He criticized the BLM ofinadequately posting signs, issuing maps for off-road users and educating people where they can and can't go, but acknowledged that, similar to boating on a lake, some people are going to act irresponsibly.

If more active management efforts don't work, he said officials need to move on to the next step. But, he added, "Closure is like going right to the finish without ever running the race."

On the other hand, Daniel Patterson, southwest director of Public Employees for Environmental Responsibility, contends that now is the time for BLM to get off-road vehicles off the monument.

Hesaid the BLM'S decision to close only a third of the monument represents a step backward from what an advisory committee - including Harper - recommended to the monument's managers at a meeting in March.

Andfigures that PEER obtained from the BLM show that off-roading now places the predominant demand on law enforcement time in the West.

From2004 through June, there were more than 2,300 incidents of illegal off-roading and more than 6,600 off-road violations for crimes including reckless driving and hit-and-run in Arizona, California, Utah, Nevada and New Mexico, and twice the number of incidents for driving under the influence involving off-road vehicles as automobiles.

The area facing closure is south of Goodyear, west of Maricopa and east of Gila Bend, said monument manager Karen Kelleher.

Shesaid there has been a major increase in motorized vehicle use since 2004-2005, when the town of Maricopa in particular started growing.

Harpersaid such increased use is seen on public lands across the country in the wake of communities whose populations have mushroomed from 15,000 or 30,000 to 100,000. "We're trying to more effectively manage that,"he said.

When then-Interior Secretary Bruce Babbitt announced the creation of the sprawling Sonoran Desert National Monument southwest of Phoenix in January 2001, a few days before Clinton left office, a proclamation said visitors could not drive off the dirt roads slicing through its 486,000 acres, or 759 square miles.

Unfortunately, a lot of people didn't pay attention.

Kellehersaid the most extensive travel and the most significant damage on the monument is north of Maricopa County Highway 238, with creosote and bursage sustaining the most damage.

"The biggest thing it doesis it breaks through the surface of the soil, what we call desert pavement, kind of the rock formation you find in the soil," she said."It destabilizes and makes the soil more vulnerable to wind and rain erosion."

She said there's one real positive.

"What wehave learned is that we can very successfully rehab these areas," she said. "We dig out the ruts and rake them and then put in dead vegetation in the ground like it's a plant, trying to mask the area so that vehicle use into the area won't occur."

PEER's Patterson said off-roaders who haven't respected the monument have displayed reckless and wild behavior.

Thisspring, the Arizona Senate came up short in a vote to require owners of off-road vehicles to pay for a new annual sticker. It would have provided money to develop trails and other access routes, grants for local enforcement of off-road vehicle laws, to mitigate damage caused by the vehicles and to create educational material, maps and signs.

TheArizona Game and Fish Department's figures show there were more than 230,000 registered or titled all-terrain vehicles in the state as of July 2006, up from 51,000 in December 1998.